The use of drug delivery devices for various types of drug therapy is becoming more common as the automated infusion of a drug may provide more reliable and more precise treatment to a patient.
Diabetes is a major health concern, as it can significantly impede on the freedom of action and lifestyle of persons afflicted with this disease. Typically, treatment of the more severe form of the condition, Type I (insulin-dependent) diabetes, requires one or more insulin injections per day, referred to as multiple daily injections. Insulin is required to control glucose or sugar in the blood, thereby preventing hyperglycemia that, if left uncorrected, can lead to ketosis. Additionally, improper administration of insulin therapy can result in hypoglycemic episodes, which can cause coma and death. Hyperglycemia in diabetics has been correlated with several long-term effects of diabetes, such as heart disease, atherosclerosis, blindness, stroke, hypertension, and kidney failure.
The value of frequent monitoring of blood glucose as a means to avoid or at least minimize the complications of Type I diabetes is well established. Patients with Type II (non-insulin-dependent) diabetes can also benefit from blood glucose monitoring in the control of their condition by way of diet and exercise. Thus, careful monitoring of blood glucose levels and the ability to accurately and conveniently infuse insulin into the body in a timely manner is a critical component in diabetes care and treatment.
To more effectively control diabetes in a manner that reduces the limitations imposed by this disease on the lifestyle of the affected person, various devices for facilitating blood glucose (BG) monitoring have been introduced. Typically, such devices, or meters, permit the patient to quickly, and with a minimal amount of physical discomfort, obtain a sample of their blood or interstitial fluid that is then analyzed by the meter. In most cases, the meter has a display screen that shows the BG reading for the patient. The patient may then dose theirselves with the appropriate amount, or bolus, of insulin. For many diabetics, this results in having to receive multiple daily injections of insulin. In many cases, these injections are self-administered.
Due to the debilitating effects that abnormal BG levels can have on patients, i.e., hyperglycemia, persons experiencing certain symptoms of diabetes may not be in a situation where they can safely and accurately self-administer a bolus of insulin. Moreover, persons with active lifestyles find it extremely inconvenient and imposing to have to use multiple daily injections of insulin to control their blood sugar levels, as this may interfere or prohibit their ability to engage in certain activities. For others with diabetes, multiple daily injections may simply not be the most effective means for controlling their BG levels. Thus, to further improve both accuracy and convenience for the patient, insulin infusion pumps have been developed.
Insulin pumps are generally devices that are worn on the patient's body, either above or below their clothing. Because the pumps are worn on the patient's body, a small and unobtrusive device is desirable. Some devices are waterproof, to allow the patient to be less inhibited in their daily activities by having to remove their drug infusion device while showering, bathing, or engaging in various activities that might subject their infusion device to moister, such as swimming. In such devices, it would be desirable to have a structure and method for verifying proper function of venting system within the device, since vents are typically passive devices that have no means for self-diagnostic checks to verify function has been compromised (i.e. intentional or unintentional obstruction of vent opening(s)). Further, it would be desirable to be able to alert the user of abnormal pressure differentials within their device that may cause erratic or unintentional drug delivery. Finally, it would be desirable for a drug infusion device to incorporate means for detecting the altitude at which the device is located, to avoid problems associated with air travel and sporting activities such as mountain climbing, skydiving, etc. that patients may wish to engage in without having to forego the use of their drug infusion device for concerns over erratic or unintentional drug delivery due to rapid pressure changes in and around the device.